Ion sources are used to ionize gasses that are introduced into the chamber of the ion source. Typically, the ion source has a plurality of walls that define a chamber. A gas is introduced into this chamber. The chamber also has an ion generation mechanism. In some cases, this ion generation mechanism may be an indirectly heated cathode, which emits electrons that serve to ionize the gas in the chamber.
Different gasses are best ionized at different temperatures. For example, larger molecules are preferably ionized at a lower temperature to insure that large molecular ions, rather than smaller ions, are created. Similarly, other species, such as carbon based species, are best ionized at higher temperatures. Additionally, the temperature of the ion source may also affect the lifetime or beam current of the ion source. Species, like carbon, may create residue in the chamber if ionized at low temperatures.
Therefore, it would be advantageous to have an apparatus that changes the temperature of an ion source between relatively hot and cold temperatures without requiring manual intervention.